The invention relates to a method of setting sheet guide elements, such as guide brackets and brush wheels or pinwheels and sheet conveying elements, such as a sheet brake on sheet-processing machines.
Published, Non-Prosecuted German Patent Application No. DE 43 21 179 A1 relates to a method and a device for controlling or regulating operating processes in a printing machine. Through the use of the method proposed in this publication, the operating person is assisted in assuring quality on a printing machine. Through the use of the method proposed in this publication, the selection of a representative color measuring location by hand or automatically, as desired, is made possible, so that a regulation is ensured, the amount of rejects is considerably reduced and the effort and costs for the control or regulation of operating processes on a printing machine are reduced. Through the use of the solution proposed in this publication, coordinates for the measurement locations of an image recording device are determined from image information which reproduces at least the surface of a printed product. At each measurement location selected in such a way, the image recording device registers a measurement field with a defined prespecified size with high accuracy on the surface of the printed product. The method may be used in particular in rotary printing machines, which contain devices for handling, printing and treating sheets or other flat materials to be printed. In addition, the method disclosed by Published, Non-Prosecuted German Patent Application No. DE 43 21 179 A1 can be used to control devices which can be provided upstream or downstream of a printing machine, such as separating apparatuses, folders, cross cutters or slitters, gatherers, stacking devices, inserting devices, insertion machines, sorting machines and delivery configurations for delivering sheet or web material.
Published, Non-Prosecuted German Patent Application No. DE 42 01 480 A1 discloses a device for depositing flat material on a stack. A control device for pressure distribution of the blown-air or suction device is provided downstream of the blown-air or suction-air devices, together with an input device, so that data relating to the two-dimensional mass distribution of the printed sheet can be taken into account. Through the use of the blown-air or suction device, a pressure distribution which is correlated with the mass distribution can be produced on the deposit surface of the sheets. The device according to Published, Non-Prosecuted German Patent Application No. DE 42 01 480 A1 is used in all machines or apparatuses in which a previously printed or coated flat article, such as a sheet or the like or another sheet-like configured product can be conveyed onto a stack and deposited on the latter with the aid of grippers and a blown-air or suction device.
The aim of a stoppage-free passage of a printed sheet through one or more printing units of a printing machine processing sheet-like material is smear-free and scratch-free sheet guidance through the entire printing machine, in which the printed upper side or the already printed underside (in the case of turning) is not damaged; and this with optimal setting of the elements guiding the sheet material, such as small brush wheels or small pinwheels or sheet conveying elements assisting the sheet guidance, such as the sheet brake. This applies basically also to other sheet guiding elements as well, such as small pinwheels rotatably mounted on a stationary axis of rotation or brush wheels in the feed plane of a feeder of a rotary printing machine. In the case of multiple systems, what often occurs, for example, in the case of four-color printing on two-color machines and where the printed-image information from the color separations from the first pass can be evaluated, the optimal setting of the elements guiding the sheet material is likewise of importance.
The position settings of the elements that assist the sheet guidance through the printing units of the rotary printing machine, and therefore the paper run, are even nowadays mostly performed manually. Remotely adjustable positioning elements are still being developed. The positioning, to be performed manually, of the sheet guide elements assisting the sheet guidance through the rotary printing machine, if it is performed in a manual way, relies heavily on the judgment and experience of the operator of the rotary printing machine who carries it out. If an unpractised operator of the rotary printing machine performs such a setting, it is entirely possible that disruptions to the printed image occur as the printing material runs through the printing units provided one behind the other in a rotary printing machine. In addition to automatic adjustment, however, it may also be practical to provide the printer with the information as a setting recommendation within the context of presetting; the information can, for example, be output on the monitor and the machine operator can be given a first starting point for a setting to be performed.
In the case of conventional configurations from the prior art, the paper run depends to a great extent on the individual experience of the persons operating the printing machine.
It is accordingly an object of the invention to provide a method of setting guide elements for a flat material along a printing-material conveying path in a rotary printing machine which overcomes the above-mentioned disadvantages of the heretofore-known methods of this general type and which uses the printed-image parameters, already known from the production of the printed original (copy preparation) before the respective current print job is printed on the multicolor rotary printing machine, to preset sheet guide elements or sheet conveying elements on the printing units of the rotary printing machine in a job-specific manner.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method of setting guide elements for a flat material along a printing-material conveying path in a rotary printing machine, the method includes the steps of:
providing sheet-guiding elements in a printing-material conveying path, the sheet-guiding elements assisting in guiding a flat material;
providing sheet-conveying elements having respective actuating positions adjustable relative to the flat material, the sheet-conveying elements influencing a sheet conveyance, the sheet-guiding elements and the sheet-conveying elements assisting a passage of the flat material through a printing machine;
initially determining a job-specifically optimized actuating position for a positioning of the sheet-guiding elements and of the sheet-conveying elements by using job-specific printed-image information known from a prepress stage; and
positioning at least one of the sheet-guiding elements and the sheet-conveying elements in relation to a printed image by using the job-specifically optimized actuating position determined in the determining step.
In other words, according to the invention, the object of the invention is achieved in that, in a method of setting guide elements for a flat material for a passage through the printing-material path on multicolor rotary printing machines, guide elements assisting the guidance of the sheet material, such as small guide wheels, guide brackets, brush wheels or pinwheels, being assigned to the printing-material conveying path, and sheet conveying elements, which influence the sheet conveyance and whose respective actuating position relative to the sheet material is adjustable, being provided, the following method steps are performed: first of all, the in job-specific terms optimal actuating position is determined for the positioning of the sheet-guiding and sheet guide elements assisting the run of the flat material through the printing machine, using the job-specific printed-image information known from the prepress stage, and
using the determined optimal actuating position, the sheet-guiding or sheet conveying elements are automatically positioned in relation to the printed image.
With the method according to the invention for the job-specifically optimized positioning of sheet-guiding or sheet guide elements, firstly the manual setup of a new print job in relation to the positioning of a sheet-guiding or sheet guide element can be omitted. The quality of the sheet guidance, that is to say the fault-free conveyance of printing material through the printing machine, no longer depends only on the expertise or the level of experience of the machine operator but can be performed automatically within the context of presetting carried out in a job-specific manner. Associated with this, one advantage of the method proposed by the invention can be seen in the fact that a considerable saving in rejects can now be achieved. Furthermore, by removing the manual intervention by the operating personnel of the multicolor rotary printing machines, the level of automation and therefore the availability of the multicolor rotary printing machine that can be operated through the use of the method proposed according to the invention can be increased considerably.
According to an advantageous mode according to the invention, the in job-specific terms optimal actuating position is determined by using the color-separation-specific area coverage present in the printed image. Therefore, printed-image information already present at the prepress stage can be used not only for the color presetting, which is carried out zone by zone, but also for the positioning of sheet-guiding and sheet conveying elements.
According to the method proposed by the invention the in job-specific terms optimal actuating positions for sheet-guiding and sheet-conveying elements can advantageously be taken into account in dependence on the local area coverage. Given appropriate weighting when determining the optimal actuating position for each job, the sheet-guiding and sheet conveying elements can be set in areas of the printed image with the lowest possible area coverage.
According to a further advantageous mode of the method proposed by the invention, the in job-specific terms optimal actuating position is determined on the basis of printed colors or shades, the optimal actuating position preferably being placed in those sections of the printed image which are occupied by lighter shades or printing inks. The configuration of a sheet guide element, be it a guide bracket provided to be stationary and having an ink-repelling coating or a rotatable guide wheel provided on a stationary shaft, can be provided significantly less critically in a yellow colored area, for example, than in a black colored area.
During the determination of the optimal actuating position according to the invention for each print job, in order to determine these positions, the state of drying of the printed ink can also be taken into account as a function of the printing unit in which guide brackets, guide wheels or other sheet-guide or sheet-conveying elements such as sheet brakes have to be adjusted or displaced.
Through the use of the method proposed by the invention, given appropriate weighting or taking appropriate account of the local printed-image information, the local effect of the elements which can have a stronger effect on the sheet trailing edge or the sheet leading edge can be taken into account as well.
By including all of the printed-image information present in the prepress stage when setting an image on the printing plate or producing an original, such information including the data relating to recto and verso printing, data relating to the finishing or varnishing of the surface of the printed image, and also data relating to the damping solution to be applied or to the selection of the printing material to be printed, these parameters can likewise be included when determining the in job-specifically optimized actuating position for sheet-guiding and sheet-conveying elements. Information relating to the presence of recto and verso printing is, for example, particularly interesting in the case of sheets printed on both sides, in which the already printed underside of the sheet is acted on by a sheet brake in order to adapt the effect of the sheet conveying element to the ability of the freshly printed underside to withstand loading, that is to say its level of curing.
Accordingly, the method according to the invention offers the possibility not only of moving to optimal, in job-specific terms particularly favorable, actuating positions or setting position but of controlling the action of sheet-conveying elements, such as a pneumatic sheet brake, in such a way that the action of the sheet brake is increased in those areas of the flat material which are uncritical; and is restricted in effect in those areas of the sheet material in which there is an increased risk of smearing.
According to the method proposed by the invention, in job-specific terms optimal actuating positions of sheet-guiding and/or sheet-conveying elements can be determined in advance with the operator within the context of an interactive operation of a touch-screen monitor. The information relating to the printed image and already known from the prepress stage can be called up on the touch-screen monitor in order to display the printed image or the printing-unit-specific color separation.
According to a variant of the method according to the invention, guide elements for the sheets used for the further print processing carried out after the printing operation, such as grippers, pins, cutting knives or the like, used in the further print processing for printing-material processing equipment can be positioned, by using the image data of the printed sheet, which is known from the prepress stage, and with knowledge of the relevant imposition scheme or output program, in such a way that any impairment to the finished printing-material surface varnished in a finishing unit is prevented.
With the method proposed by the invention, the printed-image information need not be used just for the zonal ink presetting, in which only the average zonal area coverages are determined. The prepress stage provides a whole range of job-specific data, which can be used for setting print-job-specific parameters on a multicolor rotary printing machine if, during the presetting, they can be carried out independently of the machine operator, no longer manually but now automatically through the use of actuating drives provided on the printing units of the multicolor printing machine.
According to another mode of the invention, the job-specifically optimized actuating position determined in the determining step is provided to a printer as a setting recommendation for a manual setting.
Although the invention is described herein as embodied in a method of setting guide elements for a flat material along a printing-material conveying path, it is nevertheless not intended to be limited to the details described, since various modifications and changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments.